Scientists have discovered an invisible shield roughly 7,200 miles (11,600 km) above Earth, that blocks Sun’s high-energy radiation. Illustration by Andy Kale, University of Alberta.
Sun’s high-energy radiation composed by so-called “killer electrons,” can fry satellites, degrade space systems during intense solar storms, radically change the planet’s climate and drive up rates of cancer.
What’s keeping this high-energy radiation at bay seems to be neither the Earth’s magnetic field nor long-range radio waves, but rather a phenomenon termed “plasmaspheric hiss” — very low-frequency electromagnetic waves in the Earth’s upper atmosphere that, when played through a speaker, resemble static, or white noise.
Professor Daniel Baker from the University of Colorado Boulder, said:
“It’s almost like these electrons are running into a glass wall.”
John Foster, associate director of MIT’s Haystack Observatory, said:
“It’s a very unusual, extraordinary, and pronounced phenomenon. What this tells us is if you parked a satellite or an orbiting space station with humans just inside this impenetrable barrier, you would expect them to have much longer lifetimes. That’s a good thing to know.”
This image shows a color-coded geographic representation of ultra-relativistic electron fluxes, based on orbital tracks of the Van Allen Probe B spacecraft projected onto the geographical equatorial plane. As the spacecraft processes in its elliptical orbit around the Earth, it forms a “spirograph” pattern in the Earth-centered coordinate system. Inside of this radial distance is an almost complete absence of electrons, forming the “slot” region. The superimposed circle shows a sharp, distinctive inner boundary for ultra-relativistic electrons, and how generally symmetric this boundary is around Earth. Courtesy of the reasearchers/Haystack Observatory
Mary Hudson, a professor of physics at Dartmouth College, says the data from the Van Allen probes “are providing remarkably detailed measurements” of the Earth’s radiation belts and their boundaries. She said:
“These new observations confirm, over the two years since launch of the Van Allen probes, the persistence of this inner boundary, which places additional constraints on theories of particle acceleration and loss in magnetized astrophysical systems.”
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